Method for the decomposition of halogenated organic compounds in a contaminated medium

Abstract

A method for the decomposition of halogenated organic compounds contained in a contaminated medium comprises adding an alkali metal carbonate or bicarbonate to the contaminated medium in an aqueous solution or in a solvent having a boiling point of at least 200° C., or in the form of a solid dispersion or suspension. The medium is heated to dehydrate the medium and then is further heated at a temperature between about 250° and 400° C. to effect decomposition of the halogenated organic compounds. An acid is then added to the medium in an amount sufficient to neutralize the same.

What is claimed is: 
     
       1. A method for the decomposition of halogenated organic compounds contained in a contaminated medium, comprising (a) adding an alkali metal carbonate or bicarbonate to a contaminated medium containing halogenated organic compounds, said alkali metal carbonate or bicarbonate being added as an aqueous solution or in a solvent having a boiling point of at least 200° C., or in the form of a solid suspension;   (b) heating the contaminated medium at a temperature and for a time sufficient to substantially dehydrate the medium;   (c) further heating the medium at a temperature between about 250° and 400° C. for a time sufficient to effect decomposition of the halogenated organic compounds; and   (d) adding an acid to the medium in an amount sufficient to provide the medium with a pH of from about 7 to about 9.   
     
     
       2. A method as defined in claim 1, wherein the alkali metal carbonate or bicarbonate is added in an aqueous solution. 
     
     
       3. A method as defined in claim 2, wherein the aqueous solution further contains a hydrocarbon solvent having a boiling point of at least 200° C. 
     
     
       4. A method as defined in claim 1, wherein the alkali metal carbonate or bicarbonate is added in a solvent having a boiling point of at least 200° C. 
     
     
       5. A method as defined in claim 4, wherein the solvent comprises a hydrocarbon compound. 
     
     
       6. A method as defined in claim 1, wherein the alkali metal carbonate or bicarbonate is added as a solid suspension. 
     
     
       7. A method as defined in claim 1, wherein the alkali metal carbonate or bicarbonate is added in an amount of from about 1 to about 20 weight percent based on the weight of the contaminated medium. 
     
     
       8. A method as defined by claim 7, wherein the alkali metal carbonate or bicarbonate is added in an amount of from about 2 to about 12 weight percent based on the weight of the contaminated medium. 
     
     
       9. A method as defined in claim 1, wherein the alkali metal comprises sodium. 
     
     
       10. A method as defined in claim 1, wherein the alkali metal comprises potassium. 
     
     
       11. A method as defined in claim 1, wherein the alkali metal comprises lithium. 
     
     
       12. A method as defined by claim 1, wherein the contaminated medium is heated under vacuum to dehydrate the medium. 
     
     
       13. A method as defined by claim 1, wherein in step (c) the medium is further heated at a temperature between about 250° C. and 350° C. to effect destruction of the halogenated organic compounds. 
     
     
       14. A method as defined by claim 1, wherein the acid which is added to the medium to provide a pH of from 7 to about 9 is selected from the group consisting of sulfuric acid, phosphoric acid, hydrochloric acid and nitric acid. 
     
     
       15. A method as defined by claim 1, wherein the contaminated medium comprises soil. 
     
     
       16. A method as defined by claim 1, wherein the contaminated medium comprises sludge. 
     
     
       17. A method as defined by claim 1, wherein the contaminated medium comprises sediment. 
     
     
       18. A method as defined by claim 1, wherein the contaminated medium includes an absorbent comprising spent activated carbon. 
     
     
       19. A method as defined by claim 1, wherein the contaminated medium comprises a liquid. 
     
     
       20. A method as defined by claim 1, wherein the contaminated medium contains up to 100,000 ppm of halogenated organic compounds. 
     
     
       21. A method as defined by claim 1, wherein the contaminated medium comprises a pure halogenated material. 
     
     
       22. A method as defined by claim 1, wherein the medium which results from the acid addition step is returned to its original environment.